the last time i changed my diff i was trying different bolts. i found that the bolts that goes into the gm late model trucks torque converter works great i put a little oring on them, they have a 15mm head with an allen 8mm in the middle. a little longer but there is lots of room for longer bolt. they do not have a magnet in them.
if any one should need one i think i could put in envelope and mail.
i do not know what the dealer # is.
I didnt know what the fck to remove so i got over excited using the multigrips on that fckn mushroom looking thing and ripped his head clean off hahaha